Thanks Mark,
I did manage to get the rungeKutta method working with your new
suggestions and my simple ODE worked. Cheers!

The ODE that I'm trying to solve is basically used to calculate algae
biomass over time. Therefore, dAlgae/dt = algae growth - mortality -
predation is the simplest ODE that I need to solve. Obviously,
growth, mort and predation are functions that rely on envi variables
such as light, temp, water flow etc. I'm a Phd student from the
University of Adelaide, and I'm developing a ecosystem lake model
which will solve ODEs for 2 types of algae, fish, nutrients, oxygen
and a few other things.

I'm still learning Java and OO modelling and design, so my model is
still very basic (ie. I have only focused on the algae so far). But,
now that I can solve the ODE I should be able to set up other state
variables and allow them to interact as objects (which was a main
reason for using OO paradigm).

Thanks for all your help, and no doubt I still need more!!
Lydia



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